Acc in arrears even after settlement has been paid

I am so frustrated by the poor service received from homechoice. On the 15 of December 2022 I made a payment of R6810 to settle my account. To my surprise the money apperantly was never made to their account but previous payments iv made with the same banking details appear on my statement except this one. It's been 3 months of me trying to resolve this matter with them but no one is coming to the show instead it's back and forth emails and annoying calls about my account being in arrears. This has caused my credit score to go down because it's recorded as me defaulting and not paying my account. I can't even apply for credit because of this. Please help!!!! I don't know what to do anymore.